1. Field of the Invention
The present invention relates to a high strength information recording carrier-holding sheet which can extremely smoothly house small size of thin information recording carriers such as floppy disks, slide films and so on.
2. Related Art Statement
As heretofore widely used holding sheets for arranging and storing paper mount-attached slide films as one example of the information recording carriers, for instance, there is a holding sheet shown in FIGS. 4(a) and 4(b).
According to this holding sheet, plural intermittently extending vertical partition walls 2 and plural continuously extending lateral partition walls 3 are formed in a hard plastic sheet through press molding to define a plurality of vertically and laterally arrayed rectangular depressions 5 which are capable of housing mount-attached slide films 4 of 35 mm, and planar lugs 6 are cut and raised from side walls 3a, and 3a of the opposed lateral partition walls of the rectangular depression to project into the inside of the rectangular depressions 5 while being extended up to the vertical partition walls 2.
In order to protect an emulsion-attached sheet of the slide film 4 against deformation of the bottom wall of the rectangular depression 5, this holding sheet is provided with supports 7 slightly rising at the four corners of the bottom wall of each of the depressions. Further, in order to facilitate the insertion of the slide film 4 held by two fingers into the rectangular depression 5 as well as the removal of the former from the latter, the vertical partition walls 3 are discontinued in the central portion of the depression 5 and the wall face of the vertical partition wall 2 opposed to the wall face to which the planar lugs 6 are connected is designed as an upwardly inclined surface 2a.
The insertion of the slide films 4 into the respective rectangular depressions of the holding sheet 1 is performed such that as shown in FIG. 4(a), one end of the slide film is positioned in the rectangular depression from the vertical partition wall provided with the inclined face 2a, and then the slide film is pushed thereinto until the other end of the slide film 4 is completely inserted into the rectangular depression. Consequently, the slide film 4 is supported onto the supports while being pushed down by means of the planar lugs as shown in FIG. 4(b).
Incidentally, the slide film 4 can be extremely easily removed from the rectangular depression 5 such that one end of the slide film 4 is pushed on the side of the vertical partition wall opposed to the vertical wall 2 provided with the inclined surface 2a to make the other end of the slide film 4 ride over the inclined surface 2a against the elastic forces of the planar lugs 6, 6 and further cause this other end and the near portion thereof ride over the vertical partition wall 2, thereby releasing the restraint of the slide film by the planar lugs 6, 6.
However, according to such a prior art technique, the planar lugs 6, 6 are formed in a single plastic sheet while extending from the lateral partition walls 3 to the vertical partition wall 2, and long cut holes 8 for raising the planar lugs 6 which holes extend from the side wall 3a of the lateral partition wall to the side wall 2b of the vertical partition wall while extending up to the bottom wall of the rectangular depression are obliged to be provided under the lower side of the planar lugs for the formation of the planar lug 6. Therefore, the rigidity of the holding sheet 1 is lowered by long cut holes 8 present at two per one rectangular depression 4, so that when the holding sheet 1 housing a number of the slide films 4 is lifted by holding, for instance, one corner or one side of the holding sheet 1, the holding sheet 1 is largely bent. Thus, there is a fear that the emulsion face of the slide film 4 is damaged by the bottom wall of the rectangular depression 5. In addition, there is also a problem that stress concentration occurs at the edge portion of the cut hole 8, and the holding sheet begins to be damaged from this edge portion at a relatively earlier stage.
This is more serious particularly in the case of an information recording carrier which has a relatively larger weight than the paper-mount attached slide film 4, for instance, a small size of floppy disk housed in a plastic case, a glass film in which a mount is attached to a slide film held between glass sheets, and so on.
In order to solve such problems, it has been proposed that the size of the cut holes are each made smaller by, as shown in FIGS. 5(a) and 5(b), forming the planar lugs 16 and 16 in the substantially central portions of the opposed vertical partition walls 12 in each of the rectangular depressions 15 defined by the lateral and vertical partition walls 12 and 13 to increase the rigidity of the holding sheet 1.